[PATCH] i386, apic: clean up the APIC code

The apic code is quite unstructured and missing a lot of comments.

- Restructure the code into helper functions, timer, setup/shutdown,
  interrupt and power management blocks.
- Fixup comments.
- Namespace fixups
- Inline helpers for version and is_integrated
- Combine the ack_bad_irq functions

No functional changes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Zachary Amsden <zach@vmware.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rohit Seth <rohitseth@google.com>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/i386/kernel/io_apic.c

@@ -1588,7 +1588,7 @@ void /*__init*/ print_local_APIC(void * dummy)
 	v = apic_read(APIC_LVR);
 	printk(KERN_INFO "... APIC VERSION: %08x\n", v);
 	ver = GET_APIC_VERSION(v);
-	maxlvt = get_maxlvt();
+	maxlvt = lapic_get_maxlvt();
 
 	v = apic_read(APIC_TASKPRI);
 	printk(KERN_DEBUG "... APIC TASKPRI: %08x (%02x)\n", v, v & APIC_TPRI_MASK);

arch/i386/kernel/irq.c

@@ -10,7 +10,6 @@
  * io_apic.c.)
  */
 
-#include <asm/uaccess.h>
 #include <linux/module.h>
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
@@ -21,19 +20,34 @@
 
 #include <asm/idle.h>
 
+#include <asm/apic.h>
+#include <asm/uaccess.h>
+
 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
 EXPORT_PER_CPU_SYMBOL(irq_stat);
 
-#ifndef CONFIG_X86_LOCAL_APIC
 /*
  * 'what should we do if we get a hw irq event on an illegal vector'.
  * each architecture has to answer this themselves.
  */
 void ack_bad_irq(unsigned int irq)
 {
-	printk("unexpected IRQ trap at vector %02x\n", irq);
-}
+	printk(KERN_ERR "unexpected IRQ trap at vector %02x\n", irq);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+	/*
+	 * Currently unexpected vectors happen only on SMP and APIC.
+	 * We _must_ ack these because every local APIC has only N
+	 * irq slots per priority level, and a 'hanging, unacked' IRQ
+	 * holds up an irq slot - in excessive cases (when multiple
+	 * unexpected vectors occur) that might lock up the APIC
+	 * completely.
+	 * But only ack when the APIC is enabled -AK
+	 */
+	if (cpu_has_apic)
+		ack_APIC_irq();
 #endif
+}
 
 #ifdef CONFIG_4KSTACKS
 /*

arch/i386/kernel/smpboot.c

@@ -600,7 +600,7 @@ wakeup_secondary_cpu(int logical_apicid, unsigned long start_eip)
 	/*
 	 * Due to the Pentium erratum 3AP.
 	 */
-	maxlvt = get_maxlvt();
+	maxlvt = lapic_get_maxlvt();
 	if (maxlvt > 3) {
 		apic_read_around(APIC_SPIV);
 		apic_write(APIC_ESR, 0);
@@ -697,7 +697,7 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
 	 */
 	Dprintk("#startup loops: %d.\n", num_starts);
 
-	maxlvt = get_maxlvt();
+	maxlvt = lapic_get_maxlvt();
 
 	for (j = 1; j <= num_starts; j++) {
 		Dprintk("Sending STARTUP #%d.\n",j);

include/asm-i386/apic.h

@@ -97,7 +97,7 @@ static inline void ack_APIC_irq(void)
 
 extern void (*wait_timer_tick)(void);
 
-extern int get_maxlvt(void);
+extern int lapic_get_maxlvt(void);
 extern void clear_local_APIC(void);
 extern void connect_bsp_APIC (void);
 extern void disconnect_bsp_APIC (int virt_wire_setup);